Conventional bar codes have varying width bars and spaces suitably printed on a label. The bar code may take any conventional form in one or more dimensions, and includes, for example, the typical one-dimensional UPC form. The UPC symbology is based on a specification enacted by the Uniform Product Code Council, Inc. of Dayton, Ohio. The typical UPC bar code includes a series or sequence of alternating dark bars and light spaces of varying widths. The bars and spaces are arranged in groups representing individual characters. The bar code starts with a left margin character and ends with a right margin character, and has a center reference character as well, with the characters provided there between representing any desired data.
Scanners, such as the NCR® 7882 model horizontal scanner, produced by NCR Corporation of Dayton, Ohio, USA, scan those lines by causing a laser beam to be repeatedly passed across the scan lines. The path of the laser beam is determined by a mirrored spinner, which is itself rotated by a motor. The manner in which lines are scanned will be described in detail below. However, a problem arises with this scanning, especially in store environments, where the noise of the motor can cause a nuisance to operators and customers alike.
In addition, in order to save power the spinner is stopped between scans, after a specific down time. However, this leads to an additional problem, that a scan can then not be performed until the spinner is run back up to scanning speed. This can take a few seconds to achieve and any such delay can cause inconvenience to customers waiting the scanning of goods they wish to purchase.
Another problem with prior art scanners is that they depend on motion or other sensors to determine if a bar code is present adjacent the scanner before powering up the spinner in order to scan the bar code. However, not all motion adjacent the scanner is necessarily a bar code to be scanned and thus the spinner can be powered up unnecessarily, which again cause both noise and unnecessary power consumption.
It is an object of the present invention to produce a bar code scanner, which obviates one or more of the problems discussed above.